Siftproof cartons



y 1970 s. SILVER 3,511,431

SIFTPROOF CARTONS 5 Sheets-Sheet 1 Filed Jan. 4, 1968 May 12, 1970 s,-M. SILVER SIFTPROOF CARTONS 5 Sheets Sheet 2 Filed Jan. 4, 1968 F IG.,5

y 1970 s. SILVER 3,511,431

SIFTPROOF CARTONS Filed Jan. 4,1968 s Shets-Sheet 5 I aw I J/ILTIJSU'J/lN I I w 0 mm May 12, 1970 s. M. SILVER SIFTPROOF CARTONS 5 Sheets-Sheet4 Filed Jan. 4, 1968 FIG] 5 Sheets-Sheet 5 Filed Jan. 4, 1968 UnitedStates Patent 3,511,431 SIFTPROOF (ZARTONS Stanley Milton Silver, 10Blenheim St., London W. 1, England Continuation-impart of applicationsSer. N 0. 607,216,

and Ser. No. 611,211, both filed Jan.'4, 1967. This application Jan. 4,1968, Ser. No. 695,786

Int. Cl. B65d /02 U.S. Cl. 229-37 17 Claims ABSTRACT OF THE DISCLOSURE Aone-piece carton of rectangular cross section having at least onesiftproof sealed end. The seal is formed by dust flaps and closure flapswith the dust flaps adhered along their entire surface to a closure flapand having at least a portion of their side edges adhesively secured tothe closure flap-supporting walls; said adhesive securing attained byslight excess width of the dust flaps; the excess width being preferablysoftened and serrated; and by crimping the closure flap-supporting wallstoward one another immediately below the dust flap side edges, formingbeaded carton edges enclosing the edges of the dust flaps.

This application is a continuation-in-part of my inventions describedand claimed in my copending applications Ser. No. 607,216, filed Jan. 4,1967, for a Method of Forming Cartons, and Ser. No. 611,211, now Pat.No. 3,394,866, dated July 30, 1968, filed Jan. 4, 1967, for a Blank forSift-proofing Cartons and Method of Making the Same.

The present invention relates to tubular, end-sealed cartons and, moreparticularly, to single-thickness cardboard cartons that aresubstantially hermetically sealed against communication between theirinterior and the exterior against loss or spoilage of their contentseither by the sifting thereof or by the intrusion thereinto of anymaterial from the exterior that is deleterious thereto.

The present invention is directed to the provision of a carton whichwill eliminate leakage therefrom or thereinto, due to imperfect sealingof its end, particularly on the end from which it has been filled. Suchimperfect sealing may result from incomplete adhesion between the dustflaps and cover flaps due to the tendency of the gluewetted dust flapsto curl away from the cover flaps, which also interferes with theadhesion of the side edges of the dust flaps with the walls of thecarton adjacent thereto. It may also result from pinholes at the cornersof the sealed carton end which frequently occur due to the fact.

that the folding of the panel walls along the fold lines is not alwaystrue and does not always produce an accurate parallelopiped, so that thewalls are not of equal width throughout their height and the side edgesof the dust flaps are, therefore, not parallel to or in contact with atleast one of the walls adjacent thereto when such flaps are infolded forsealing.

It is an object ofthe present invention to provide cartons, of thecharacter described, that are substantially completely sealed againstsifting at the corners of the end seal and between the dust flaps andthe cover flaps and the side edges of the dust flaps and the cartonwalls adjacent such side edges.

It is another object of the present invention to provide siftproofcartons, of the character described, which require no excess cardboardin their formation and may, therefore, be produced at no advance in costover standard, similar cartons heretofore in use.

It is a further object of the present invention to provide siftproofcartons, of the character described, which ice may be set up, filled andsealed with standard equipment, only slightly modified, and at standardrates of speed.

The foregoing and other objects and advantages of the siftproof cartonof the present invention will become more readily apparent to thoseskilled in the art from the embodiments of the invention more or lessschematically illustrated in the accompanying drawings, and from thedescription following. It is to be understood, however, that suchembodiments are shown by way of illustration only, to make theprinciples and practice of the invention more readily comprehensible andwithout any intent of limiting the invention to the specific detailstherein shown.

In the drawings:

FIG. 1 is a fragmentary, plan view of one form of a conventional cartonblank for a carton of the present invention;

FIG. 2 is an isometric view of the blank of FIG. 1, on

an enlarged scale, folded and glued and ready for seal- FIG. 3 is a moreor less schematic, isometric view showing the set-up carton of FIG. 2,as passing through a constant, straight-line motion, carton-sealingapparatus;

FIG. 4 is a more or less diagrammatic section taken on line 44 of FIG.3;

FIG. 5 is an isometric view of the sealed end of the carton coming offthe apparatus of FIG. 3;

FIG. 6 is a foreshortened, top plan View of another,

FIG. 7 is an isometric view of the folded and glued blank of FIG. 6, setup in readiness for sealing with thedust flaps and cover flaps severedfrom one another and ready for folding and sealing;

FIG. 8 is a more or less diagrammatic view illustrating the folding andsealing of an end of a carton made from the blank of FIG. 6 on apparatussimilar to that of FIG. 3; 1

FIG. 9 is a section taken on line 9-9 of FIG. 8; and

FIG. 10 is a section taken on line 10-10 of FIG. 8.

FIG. 11 is an isometric view, partly in section, of the sealed endcarton of FIG. 7.

Generally stated, the formation of a siftproof carton seal may beeffected by assuring that the dust flaps are directly in contact, alongtheir top surfaces, with the overlying cover flaps and that their edgesare in contact along their entire lengths with the Walls of the cartonadjacent thereto, especially at the corners, so that the adhesive willpositively connect such surfaces and such edges with the adjacent cartonportions. Such contact and adhesion may be effected in a number of ways.One way is by the provision of an excess amount of adhesion along themarginal side edge portion of the dust flaps that will, when the coverflaps are pressed against them,

be compressed into any gaps or holes left when the dustflaps areinwardly folded to fill such gaps or holes.

A more effective seal may be attained by also, at the time of foldingthe cover flaps 0n the dust flaps, compressing inwardly the marginaledge portions of the walls adjacent the side edges of the dust flaps topress such wall portions against such side edges and to more positivelycontact the excess of the glue that is pressed from the upper surfacewhen the cover flaps are pressed against such surface. Such compressionwill also inhibit the inward curling of the glue-wetted dust flaps andtheir continued contact with the cover flaps. Such compression will alsoleave a rib-like formation or chine on the end edges of such adjacentwalls.

Still more effective siftproofing may be attained by slightly wideningeach dust flap at each side edge thereof and the breaking up andsoftening of the fibrous structure of the excess width portions, torender them compressible and to fill any gap that may be present anddirectly contact the adjacent side walls and become compressed anddirectly glued thereto. The effects of this construction may likewise beenhanced by the inward compression of the end edge portions of the sidewalls adjacent to the dust flaps in the direction of the side edges ofthe dust flaps.

In the last embodiment, the excess width of the dust flap, instead ofbeing continuous, may be interrupted by regularly-spaced recesses toprovide a serrated tooth-like formation. The recesses will receive aquantity of the sealing adhesive which, when the excess width iscompressed, will be pressed out from the recesses to ensure the completeadhesion of the edges of the dust flaps to the adjacent side walls ofthe carton, as well as to the edges of the overlying closure flaps, toproduce a substantially hermetic seal at that end of the carton.

Referring now in detail to the accompanying drawings and with particularreference to FIGS. 1 to 5, inclusive, thereof, the same show a cartonblank of conventional type cut and scored to have front and rear wallpanels, and 12, respectively, each formed with an end wall-forming flapat each of its ends (only one end shown), designated as 14 and 16,respectively, and defined from panels 10 and 12 by fold lines and 17,respectively; and the end wall panels, 18 and 20, each formed with aninner dust flap, 22 and 24, respectively, at each of its ends (only oneend shown). A terminal panel of the blank, such as rear wall panel 12,is provided with a glue flap, 26, along its free edge. Dust flaps 22 and24 are preferably of a height not greater than half the width of a panel10 and 12, and closure flaps 14 and 16 are preferably of a lengthgreater than half the width of an end wall 18 and 20. Where the glueflap 26 of the blank is formed along the edge of a front or rear wallpanel 10 or 12, as illustrated, its extension at each end, 22a, becomespart of the dust flap at the other edge of the blank, as 22, when theblank is folded and glued, as shown in FIG. 2.

The folded and glued blank, set up in tubular form (FIG. 2), may bemoved for end sealing, in upright position, on a constant motion,straight line, end sealing apparatus of generally conventional type(FIG. 3), between guide rails 36, of the apparatus, with the front andrear walls 10 and 12 disposed against the guide rails, as indicated bythe arrow.

As conventional, the erected carton, in its initial position in theapparatus, has its flaps upwardly extending, as shown at position A. Thecarton is then moved to position B, where dust flaps 22 and 24 arefolded to horizontal position, over the carton opening, and endwallclosure flaps 14 and 16 are laterally outwardly offset, to overlie therails 36. The carton is then moved to position C, in the course of whichmovement an adhesive layer, 30, is applied to a selected pair of flapsfor adhering one of the end wall forming flaps, as 14, to the dust flaps22 and 24 and the other end wall closure flaps, 16, to flap 14.

The adhesive 30 may comprise a glue or a thermoplastic material. It maybe applied to the upwardly facing surfaces of the outwardly offset endclosure flaps 14 and 16 as illustrated, or to the upwardly facingsurface of the inwardly offset dust flaps 22 and 24 and to the surfaceof end closure flap 16; both practices being conventional. When theadhesive 30 is applied to the selected flaps, a thickened band ofadhesive is applied to their marginal edge portions closest to walls 10and 12, as indicated at 32', whether such adhesive is in liquid form, asglue, or in the form of a thermoplastic material, which may be melted bythe application of heat at the appropriate position on the end sealingapparatus, by conventional heated knives.

The thickened band of adhesive 32, when in glue form, may be applied inany one of a number of ways, as by suitably notching the wiping ordoctor blade of the gluer (not shown) so as to leave a thicker layer ofadhesive on the appropriate edge of each of the gluing drums, 33, or bythe use of a second set of gluing drums in tandem with the drums 33.Preferably the band of thicker layer of adhesive may be so applied thatit slightly overlaps the edges of those flaps to which it is applied.When adhesive or glue is applied to flaps 14 and 16, a narrow band ofglue may at the same time be applied to the marginal portions of theside edges of dust flaps 22 and 24, to provide an excess of glue alongthese portions on the closing of the flaps 14 and 16.

Thereafter, the carton is moved toward position D, in the course ofwhich movement the flap 16 is plowed into horizontal position to overliedust flaps 22 and 24 and the adhesive-coated closure flap 14 is thenplowed to overlie closure flap 16. From this position, instead of havingthe flaps pressed against one another to form the carton seal, as isconventional, the present invention provides, at position E, for thegradual compression or pinching of the front and rear panels 10 and 12slightly towards one another, at a point immediately adjacent the foldlines 15 and 17, to inhibit the inner movement or curling of dust flaps22 and 24. Such pinching may be accomplished by applying to the innersurfaces of the guide rails 36 of the apparatus, at that location,relatively thin shims forming pinch rails, 38, whose lead edges aretapered toward their supporting guide rails, to thereby gradually pinchthe wall panels 10 and 12 toward one another and effect a compressionwithout risk of damage to the carton walls. Substantially simultaneouslywith the pinching operation, pressure is applied, likewise progressivelyand gradually, to the outer closure flap 14, from the exterior, to pressall of the flaps together to form the seal; the pressure being appliedonly slightly behind the application of the pinching pressure by thepinch rails 38. Such pressure application may be in any conventionalmanner, as by means of a pressure plate, 40, shown in the drawings inbroken lines, for clarity of illustration, or by rollers. Preferably thedegree of pinching is relatively slight, totaling approximatelyonesixteenth of an inch 0/ or -inch on each side.

It may here be stated that the shims 38 may be permanently coated with aplastic lubricant of the type that is frequent y used on the guide railsthemselves, to reduce the friction on the cartons moving between them.

The shims or pinching rails 38, in addition to preventing the inwardcurling of the inner dust flaps 22 and 24 which are glue-wetted, alsoserve to bring the upper edges of the front and rear walls 10 and 12into contact with the line of thickened adhesive 32 which is pressedfrom between the adhesive-coated flaps under pressure of plate 40, atleast at the points at or adjacent the corners of the carton, even whenthe flaps 22 and 24 are not entirely parallel to walls 10 and 12, toassure the filling in and sealing of such corners by a direct adhesionbetween the sides 10 and 12 with the edges of flaps 22 and 24 andthereby produce a sealed end c osure for the carton which is siftproof.

FIGS. 6 to 10 of the drawings illustrate a preferred embodiment of thesiftproof carton of the invention and the blank from which it may beformed. The blank (FIG. 6) is, in most respects, conventionally cut andscored to provide the same panels and flaps as the blank of FIG. 1,which are similarly numbered. It departs from the blank of FIG. 1,however, in the following respects:

Dust flaps 22 (which include flap portions 22a when the blank is foldedand glued) and 24 (FIG. 6) are slightly wider than their supporting wallpanels 18 and 20, respectively; the excess width being taken from thecover flaps 1'4 and 16 and from glue flap extension 22a, which borderthe dust flaps on their respective side edges. Further, the excess widthportion of the dust flaps are processed to weaken the fibre structureand render them readily yieldable to folding and compression.

In the most preferred embodiment, the excess width portions of the dustflaps are serrated to provide, preferably, substantially even-sized,evenly-spaced teeth-like formations or projections 50 separated byspaces 52. The innermost of the teeth 50 are preferably connected to thewall panels supporting the adjacent cover flaps 14 and 16, as the casemay be.

. The width and height of the teeth and the width and depth of thespaces between them maybe on the scale of about of an inch.

The teeth or projections 50 may most conveniently be formed by provisionof closely-spaced parallel rows of closely-spaced cuts between the dustflaps 22 and 24 and glue flap 22a, and the adjacent closure flaps 14 and16; one of the rows, as 53, being in substantial alinement with the foldline defining wall panel 18 from wall panel and wall panel 20 from wallpanels 10 and 12 and glue flap 26 from wall panel 12; the other of therows of cuts 54 being formed in the closure flaps 14 and 16. The cuts ineach of the pairs of rows 53 and 54 are preferably staggered relative toone another and they form tear-lines which, when torn, provide teeththat project from each side edge of dust flaps 22 and 24. Teeth on oneof the side edges of dust flap 22 are supplied by the glue flapextension 22a when the blank is glued and folded. The method and meansfor forming the closely-spaced rows of intermittent cuts 53 and 54 andof simultaneously weakening the fibre structure of the excess width andadjacent portions of dust flaps 22 and 24 are more fully described andclaimed in my copending application 'Ser. No. 607,217, filed Jan. 4,1967.

The embodiment of the blank for the carton of FIGS. 6 to 10, inclusive,further departs from the conventional in that the fold-lines 56 and 58,respectively, defining them from wall panels 10 and 12, respectively,are not straight, as is conventional, but are arched or pointed in thedirection of the respective dust flaps. The blank of FIG. 6 furtherdistinguishes over the conventional in that each of dust flaps 22 and 24is provided with at least one foldline 60 and 62, respectively,extending longitudinally from the respective fold-lines 56 and 58.

' In order to .seal. the end of a carton formed from the blank of FIG.6, the flat-folded and glued blank is opened into rectangularcross-section and the tear-lines between the dust flaps 22 and 24 andclosure flaps 14 and 16 opened, as more clearly shown diagrammaticallyin FIG. 7 and then passed through the apparatus of FIG. 8, which issimilar to the apparatus of FIG. 3. Preferably, mechanism for openingthe tear-lines may be provided at the entry end of the apparatus.However, such tear-line opening means does not constitute any part ofthe present invention and it it not illustrated in the drawings.

It will be clear that since dust flaps 22 and 24 are slightly wider thanthe distance between walls 10 and 12, they are held in fixed relativeposition between rails 36 of the apparatus, the folding of such dustflaps over the opening between walls 10 and 12, as the carton progressesover the apparatus of FIG. 7, from station A to station B, will causethe excess width of the dust flaps to overlie the end edges of walls 10and 12. It will a so be apparent that as closure flaps 16 and 14 arefolded over the dust flaps as the carton progresses from station C tostation D, they will exert pressure on the edges of the dust flapswhich, because of the shape of the foldlines 56 and 58 at bases and thepresence of the foldlines 60 and -62 at their midpoints, and becomelongitudinally peaked along the center fold-lines '60 and 62, as more orless diagrammatically illustrated in FIG. 9 of the drawings. It will beunderstood that because the side edges of the dust flaps overlie the endedges of walls 10 and 12, their curling inwardly when wetted will beinhibited even in the initial stage of sealing. Such inhibition will begreatly enhanced when the carton reaches the time the closure flaps arefolded over them, the dust flaps will offer resistance to the closureflaps, as they are folded over them, so that complete adhesion will beef-i fected between them when the carton moves under 'pressure of block40.

It will be seen from the diagrammatic illustration of FIG. 9 that theconfining of the carton walls 10 and 12 between the rails 36 of theapparatus, with or without the use of shims 38, will cause the excesswidth of the dust flaps 22 and 24 to move downwardly into the carton ascover flaps 14 and 16 are folded thereover; this being the onlydirection in which such excess width is free to move. This will resultin a positive contact between the edges of the dust flaps 22 and 24 andcarton side walls 10 and I12 along the entire length of the dust flapedges, to thereby provide a siftproof seal.

The'siftproof characteristics of the seal will be enhanced where theexcess width of the dust flaps 22 and 24 is serrated, because thecoating of glue as it is applied to the surface of the dust flaps eitherdirectly or indirectly will penetrate into the spaces between theserrations or teeth 50 and when such serrations are compressed asheretofore explained, the glue in the spaces between them will bepressed out, to form a positive adhesion between the side edges of thedust flaps and the adjacent side walls contacting them, to result inalmost a hermetic seal between them. The softening of the excess widthof the dust flaps when it is serrated, where effected, will still moreperfectly seal the carton end because the softened fibre structure ofthe edges of the dust flaps will spread to substantially fill the spacesbetween the teeth and press more of the glue out of such spaces. 1

This completes the description of the siftproof cartons of the presentinvention and the methods by which they are formed. It will be readilyapparent that the cartons of the invention are highly effective fortheir purpose and that they may be formed, set up, filled, and sealed asrapidly and as economically as similar, conventional cartons asheretofore used.

It will also be apparent that numerous variations and modifications maybe made in the siftproof cartons of the present invention, in accordancewith the principles of the invention hereinabove set forth, by anyoneskilled in the art, without the exercise of any inventive ingenuity.

What I claim is:

1. A cardboard carton comprising two pairs of opposed wall panelsconnected to One another along their entire lengths, the wall panels ofone of said pairs of wall panels each having a dust flap extending fromat least one end thereof, each said dust flap having parallel sideedges, the wall panels of the other of said pairs of wall panels eachhaving a closure flap extending from its corresponding end; each saiddust flap folded over the opening defined by said two pairs of wallpanels; said cover flaps folded over said dust flaps, and a layer ofadhesive provided between said cover flaps and said dust flaps securingthem to one another, said layer of adhesive extending over the sideedges of said dust flaps at least at their inner ends and contacting theinner surface of the wall panels of said other pair at least at theirinner ends; said dust flaps having slight lateral enlargements at leastat the inner end of each side edge thereof whereby at least the innerend of said dust flaps are of greater width than the distance betweenthe other of said pairs of wall panels and are compressed against them.

2. The carton of claim 1, wherein the portion of the wall panels of saidother pair of wall panels, immediately adjacent the portions thereofcompressed against; the side edges of said dust flaps, slightly underliethe compressed edge portions of said dust flaps.

3. The carton of claim 1, wherein said dust flaps have slight lateralenlargements at least at the inner end of each side edge thereof, saidadhesive extends over said enlargements and said enlargements compressedagainst the adjacent portions of the wall panels of said other pair ofwall panels.

4. The carton of claim 3, wherein said enlargements have a weakenedfibre structure.

5. The carton of claim 4, wherein said slight enlargements extend theentire length of the side edges of said dust flaps.

6. The carton of claim 5, wherein the portion of the wall panels of saidother pair of wall panels, immediately adjacent the side edges of saiddust flaps, are compressed towards one another to slightly underlie saiddust flaps.

7. The carton of claim 5, wherein said slight enlargements are serrated.

8. The carton of claim 7, wherein said serrations are closely and evenlyspaced from one another.

9. The carton of claim 7, wherein said adhesive extends into the spacesbetween said serrations.

10. The cardboard carton of claim 1, wherein said dust flaps are definedfrom their connected wall panels by a fold line and each has alongitudinally-extending fold line formed therein at a midpoint thereofand oriented for folding in the same direction as said first-named foldlines.

11. The cardboard carton of claim 1, wherein said dust flaps are eachdefined from their connected wall panels by a fold-line of irregularshape and having an apex extending in the direction of the dust flaps,and a longitudinally-extending fold-line is provided in each said dustflap, at a midpoint thereof, oriented for folding in the same directionas said flap-defined fold-line and extending outwardly from saidfold-line.

12. A one-piece tubular carton having pairs of opposed Wall panels, saidcarton sealed at at least one end thereof, said seal formed of dustflaps and closure flaps hingedly connected to said wall panels, saiddust flaps being wider at least at the point adjacent theirwall-connected ends than the distance between the walls connected tosaid cover flaps, at least the edges of the wider portions of each saiddust flap being defibrillated, said carton having a bead formed on twoopposed corner edges thereof at said end, said Ibeads being eachcomposed of a portion of at least one closure flap and a portion of thewall panel to which said closure flap is hinged, said head extending thelength of said corner and enclosing at least a portion of one edge ofeach of said pairs of dust flaps.

13. The carton of claim 12, 'wherein the edges of said dust flapsenclosed within said beads are adhesively secured to the inner surfaceof said beads 14. The carton of claim 13, wherein at least a portion ofsaid side edges of said dust flaps have tiny recesses formed therein andsaid recesses are substantially filled with adhesive material.

15. A glued and flat-folded blank for a tubular carton, said blankformed of a unitary section of sheet material such as cardboard andhaving fold-lines scored therein to define wall panels, and at least atone end thereof a plurality of flap extensions of said wall panelshingedly connected to said wall panels, said flap extensions includingtwo dust flaps, said dust flaps having parallel side edges conditionedto have there the width between said two opposed side edges thereofreduced when pressure is applied against said side edges as the blank isset up and sealed.

16. The carton blank of claim 15, wherein said flaps include a pair ofclosure flaps and said dust fiaps and closure flaps are partially joinedtogether by a tear-line formed of a pair of closely-spaced parallellines of staggered intermittent cuts, one of said lines of cuts beingcontinuous with the fold-lines separating the dust flapsconnected wallpanels from their adjacent wall panels, and the other of said lines ofintermittent cuts formed in the adjacent closure flaps intermittentportions of cardboard fibre.

17. The carton blank of claim 15, wherein said dust flaps are each of awidth slightly greater than the wall panel to which it is hinged.

References Cited UNITED STATES PATENTS 88,165 3/1869 Hendryx 229-301,199,535 9/1916 Feeley 229-38 1,976,980 10/ 1934 Bergstein 229-37 XR2,341,845 2/ 1944 Mark et a1 229-37 2,415,869 2/1947 Coleman 229-372,524,032 10/1950 Back 53-47 2,830,505 4/1958 Guyer 229-37 XR 3,126,1433/1964 Hagan 229-37 3,194,473 7/ 1965 Rumberger 229-37 3,297,229 1/ 1967Bluem 229-37 3,341,105 9/1967 Curran 229-37 3,366,308 1/ 1968 Phillips.

3,394,866 7/1968 Silver 229-37 D. T. MOORHEAD, Primary Examiner

